High-voltage circuit breaker equipped with means for placing a resistor in parallel with the breaker contact during breaker closing operations

ABSTRACT

A high-voltage circuit breaker has a primary switch, an auxiliary switch and a resistor connected in series with said auxiliary switch. The serial combination of the resistor and the auxiliary switch is in parallel with the primary switch. The primary switch and the auxiliary switch have a common mechanical drive movable to various positions for actuating the switches. The auxiliary switch has a spring for holding it in the open position and a force-coupled connector is provided for forcecoupling the drive to the auxiliary switch. The connector is disengageable from the drive in dependence upon the position of the drive. When the breaker operates, the auxiliary switch closes prior to the closing of the primary switch and opens again after the primary switch is closed.

I [22] Filed:

Noaclt Uct. 2,1973

1 1 HIGH-VOLTAGE CIRCUIT BREAKER EQUIPPIEI) WITH MEANS FOR PLACING ARESISTOR IN PARALLEL WITH TllllE BREAKER CONTACT DURING BREAKER CLOSINGOPERATIONS [75 I Inventor: Dieter Noacls, B e rlin, Germ any [73]Assignee: Siemens Alttiengesellschaft, Munich,

Germany Apr. 3, 1972 [2]] Appl. No.: 240,514

[52] US. Cl. 200/148 11), 200/144 AP [51] Int. Cl. Ill0lh 33/60 [58]Field of Search 200/148 B, 148 D,

. ZOO/148 R, 144 AP [56] References Cited UNITED STATES PATENTS3,163,737 12/1964 Gonek et a1. ZOO/148 D 3,390,239 6/1968 Miller 200/148B FOREIGN PATENTS OR APPLICATIONS 979,029 12/1950 France 200/148 D6,606,312 11/1966 Netherlands 200/148 D Primary ExaminerRobert S. MaconAttorney-Hugh A. Chapin [57] ABSTRACT A high-voltage circuit breaker hasa primary switch, an auxiliary switch and a resistor connected in serieswith said auxiliary switch. The serial combination of the resistor andthe auxiliary switch is in parallel with the primary switch. The primaryswitch and the auxiliary switch have a common mechanical drive movableto various positions for actuating the switches. The auxiliary switchhas a spring for holding it in the open position and a forcecoupledconnector is provided for force-coupling the drive to the auxiliaryswitch. The connector is disengageable from the drive in dependence uponthe position ofthe drive. When the breaker operates, the auxiliaryswitch closes prior to the closing of the primary switch and opens againafter the primary switch is closed.

17 Claims, 3 Drawing Figures PATENTED UB1 2 I973 SHEET 10F 2 'PATENTEU091 2 75 SHEET 2 [IF 2 HIGH-VOLTAGE CIRCUIT BREAKER EQUIPPED WITII MEANSFOR PLACING A RESISTOR IN PARALLEL WITH THE BREAKER CONTACT DURINGBREAKER CLOSING OPERATIONS BACKGROUND OF THE INVENTION The inventionrelates to a high-voltage circuit breaker having a primary switch, aresistor and an auxiliary switch connected in series with the resistor,the serial combination of the resistor and auxiliary switch beingconnected in parallel with the primary switch. More particularly, theinvention 'relates to such a breaker equipped with a force-coupledconnector for providing a force'coupling between the auxiliary switchand the breaker drive in dependence upon the position of the drive.

It is an object of the invention to provide a highvoltage circuitbreaker wherein the reliability of switching is increased.

It is another object of the invention to provide a highvoltage circuitbreaker having a simple drive mechanism.

Subsidiary to the foregoing objects, it is an object of the invention toprovide such a circuit breaker wherein the proper time sequence ofactuating the primary and auxiliary switches is maintained to a degreeof accuracy higher than that obtained with known compressed-gas circuitbreakers.

In the above-mentioned compressed-gas circuit breakers the switches aremutually coupled only by pneumatic means as disclosed for example inDeutsche Auslegeschrift 1, 086,780.

According to a feature of the invention, a common drive is provided forthe auxiliary switch and primary switch of the breaker. The auxiliaryswitch has a spring for holding it in the open position as well asforcecoupled connector for force-coupling the drive to the auxiliaryswitch in dependence upon the position of the drive, or statedotherwise, the force-coupled connector is disengaged in dependence uponthe position of the drive.

In the circuit breaker according to the invention, a common actuatorprovides that the desired timing sequence of actuating the primary andauxiliary switches is precisely maintained for the essential switchingoperation, especially, the closing operation. The desired timingsequence is assured because of a rigid mechanical connection. Differentswitching times can be obtained, for example, by means of differentangular positions of the crank arms of a common drive shaft. The anglebetween the crank ar'ms provides the difference of timing desired forthe switching operation.

The connection between auxiliary switch and drive which can bedisengaged in dependence upon the distance travelled makes it possibleto place a load on the resistor for only a short period of time. Forexample, a switch closing resistor that is intended to reduceovervoltage when switching in a high-voltage line need only be used whenthe circuit breaker is closed and not when it is open.

The connection that is disengageable is dependence on distance travelledcan be realized by actuating the auxiliary switch with a crank and a rodhaving a slot in which a pin of the crank is engaged, the free movementof the crank pin being blocked in dependence upon position. The block tothe movement of the crank pin in the slot permits the connection totransmit a force. If

the limitation or block is removed, the slot affords sufficient spacethat the spring of the auxiliary switch that urges this switch into theopen position is free to function.

According to a preferred embodiment of the invention, a stop cam isarticulately joined to the end of the rod facing the auxiliary switch.The stop cam coacts with the crank pin and acts against the force of aspring in the end position of the crank so as to be displaceable fromthe blocking position. Preferably, the spring is a leaf spring. The leafspring can hold a one-arm lever in the blocking position. The one-armedlever functions as the stop cam and is accommodated in a fork-shapedcrank arm. The stop cam is forced from the blocking position only at theend of the crank motion.

The circuit breaker according to still another and advantageous featureof the invention, the auxiliary switch has a butt contact with a movablecomposite contact pin that can be shortened against the action of aspring; this spring forms part of the composite pin. Such a butt contactcan open and close with a minimum of pre-discharge phenomena. The springof the composite pin adapts the switching movement to the spacingbetween contacts of the auxiliary switch.

The circuit breaker of the invention is especially suitable for veryhigh-voltages, for example, for 380 KV and higher. According to anotherembodiment, it is preferable to arrange two primary switches and twoauxiliary switches on the same axis so as to be symmetrical with respectto each other and to operate all the switches with the same actuator.

Although the invention is illustrated and described herein as ahigh-voltage circuit breaker, it is nevertheless not intended to belimited to the details shown, since various modifications may be madetherein within the scope and the range of the claims. The invention,however, together with additional objects and advantages will be bestunderstood from the following description and in connection with theaccompanying drawings discussed below.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagramillustrating the principle components of the high-voltage circuitbreaker according to the invention.

FIG. 2 is an elevation view of the circuit breaker of the inventionshowing a break-out view, partially in section, of the operating partsof the auxiliary switch.

FIG. 3 is a schematic diagram, in perspective view, of a high-voltagecircuit breaker equipped with two auxiliary and two primary switchesaccording to an alternate embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electric high-voltagecircuit breaker shown in FIG. 1 has a switching chamber 7 with primaryswitch 6. A series circuit consisting of a resistor 12 and an auxiliaryswitch 10 is connected in parallel with switch 6. The auxiliary switch10 and the resistor 12 are mounted together in a tube 111 made ofinsulating material. The primary switch 6 and the auxiliary switch 10are driven by mechanical drive means comprising a common drive in theform of an actuator member 4. The actuator member 4 can in turn bedriven by a double-action hydraulic or pneumatic cylinder 101. Theprimary switch 6 and the auxiliary switch 10 thus a common mechanicaldrive. In addition, a force-coupled connecting means in the form ofdevice 29, 30 is provided between the auxiliary switch and the actuator4. The device 29, 30 is disengageable in dependence upon position; thiswill be explained in greater detail below.

Referring now to FIG. 2, the support insulator l supports a metallicdrive housing 2, in which a two-arm crank 3 is securely mounted on aswitching shaft 4. The switching shaft 4 is actuated by an actuatingdevice that is preferably a hydraulic drive at ground potential. Aprimary switch 6 is located within the switching chamber 7 and iscoupled to switching shaft 4.

An auxiliary switch 10 and the switch-closing resistor 12 are connectedelectrically in shunt with the primary switch 6. The switch 10 andresistor 12 are mounted in tube 11. The auxiliary switch 10 includes afixed contact 14 and a movable, two-part contact pin 15. The compositecontact pin includes a forward part 17 and a rear part 19. A spring 16urges the forward part 17 of the composite contact pin outwardly, theforward part 17 being directed by guide 18 of the rear part 19; thispermits the length of the contact pin 15 to be shortened. A slidecontact 20 provides for the message of current from the contact pin 15to the drive housing 2.

A spring plate 23 is attached at the end of the composite contact pin 15facing away from the stationary contact 14. A pressure spring 24 bearsagainst plate 23 and biases the contact pin 15 in the direction ofswtich opening. For switch closure, the contact pin 15 is actuated witha rod 26 that is pivoted at the spring plate 23 at location 27. The rod26 is part of the force-coupled connection means and has an elongatedopening or slot 29. A crank 3 with crank pin 30 also constitutes part ofthe force-coupled connection means. The crank pin 30 of the crank 3engages the slot 29 and, in this way, a lost-motion connection isprovided which can be blocked in dependence upon position. Blockingaction is provided by blocking means comprising a stop cam 32 pivotally'mounted on pin 27. The cam 32 is urged by a leaf spring 33 into theposition shown in FIG. 2 in solid outline. In this position the cam edge35 limits the free movement of the crank pin 30 in the slot 29. Only atthe end of a rotary movement which brings the crank 3 into the other endposition is the block to the pin 30 removed. There, displacement meanscomprising a projection 36 of the cam 32 hits a stop or abutment 37 andswings the stop cam 32 out of the path of the crank pin 30 in the slot29 as shown in phantom outline at 40.

The switching operation of the circuit breaker according to theinvention will now be described with reference to FIG. 2.

The breaker is shown in the open position and the primary switch 6 andthe auxiliary switch 10 are both open. For closing the breaker, theswitching shaft 4 is rotated counterclockwise by means of intermediatemembers not shown. The different angular positions of the crank arms ofthe primary and auxiliary switches ensure that the auxiliary switch 10closes first, because the crank pin 30 pushes against the compositecontact pin 15 by means of the stop cam 32 and the rod 26, so

that the contact pin 15 is moved against the action of the spring 24 inthe direction of closing.

The tip of the contact pin 15 coacts with the station ary contact 14 inthe manner ofa butt contact, the contact 14 having a somewhat conicalcontour at the region of contact. Because this contact occurs prior tothe closing of the primary switch, the capacitances of the line to beconnected are charged through the resistor 12.

The closing of the primary switch 6 takes place with a time delaydetermined by the characteristic impedance and the capacitances of thehigh-voltage line to be connected as well as by the resistor 12. Afterthe primary switch 6 is closed, auxiliary switch 10 is again opened asthe crank 3 retracts the contact pin 15 after passing the extendedposition. In this connection, the crank'3 is aided by the spring 24. Atthe end of the pivot movement, the projection 36 strikes the surface 37and removes the block that the stop cam 32 applies to the crank pin 30in the slot 29, so that the spring 24 can bring the contact pin 15 intothe open end position. The primary switch 6 remains closed as theauxiliary switch 10 is brought to the open position.

The auxiliary switch 10 is not actuated when the breaker is openedbecause the connection between the rod 26 and the crank 3 is disengaged.Only in the end position of the switch opening movement, does the crankpin 30 occupy such a position in slot 29 that the stop cam 32, under theaction of the leaf spring 33, can drop into the position shown, in whichthe lost-motion connection is blocked. The resistor 12 need therefore bedetermined only for the closing current.

FIG. 3 illustrates an alternate embodiment of the high-voltage circuitbreaker equipped with two primary switches 6 and two auxiliary switches10 as well as two resistors 12; the configuration being symmetrical withrespect to\the switching shaft 4. v

The switching shaft 4 is rotatably supported in bearings 110 that arefixed with respect to the housing. The crank 3 is carried at one end ofthe shaft 4 and is connected rigidly with the shaft 4 so as to permit norotational shift. On the shaft 4 are mounted two directionchanginglevers 108 and 109, which are coupled, on the one hand, with the primaryswitches 6 and, on the other hand, with a drive rod 104 through levers106 and 107. The drive rod 104 is guided for vertical movement in athrust bearing that is fixed with respect to the housing. By means ofthe direction-changing levers 108 and 109, the vertical motion of thedrive rod 104 is transformed into a reciprocating motion at right anglesto the vertical motion for the primary switches 6. Teedirection-changing lever 108 is ridigly connected with the shaft 4 toprevent rotational shift whereas, the direction-changing lever 109 issupported on the switching shaft 4 so as to be freely rotatable. Thedrive rod 104 is actuated via a direction-changing lever 103 and aconnecting rod 102 by a double-acting hydraulic or pneumatic cylinder101.

When the drive rod 104 is moved, the switching shaft 4 is forced torotate together with the directionchanging lever 108, so that a rigidmechanical coupling results between the direction-changing lever 108 andthe crank 3 and thereby also a rigid mechanical coupling between theprimary switch 6 and the auxiliary switch 10. The mode of operation ofthe circuit breaker shown in connection with FIG. 2 applies during theswitching operation and like parts are designated with the samereference numerals.

FIG. 3 also shows that the primary switches 6 and the auxiliary switches10 are arranged on the same axis symmetrically with respect to eachother and are actuated by the same drive 101, 102, 103 and 104.

What is claimed is:

LA high-voltage circuit breaker comprising a primary switch; anauxiliary switch; and a resistor connected in series with said auxiliaryswitch, the serial combination of said resistor and said auxiliaryswitch being connected in parallel with said primary switch; mechanicaldrive means comprising a common drive movable to different positions foractuating said switches; said auxiliary switch comprising a spring forholding said auxiliary switch in the open position; and force-coupledconnection means for force-coupling said drive to said auxiliary switchand for disengaging said drive in dependence upon the position of saiddrive, said auxiliary switch further comprising a set of two contacts,at least one of said contacts being a movable contact connected to saidforce-coupled connection means for contacting the other of said contactin a butt-like manner when said auxiliary switch is closed, said movablecontact being a composite member comprising a rear part connected tosaid force-coupled connection means, a forward part for contacting saidother contact, said forward part being longitudinally displaceable withrespect to said rear part to an extended position for increasing thetotal length of said movable contact, and a spring disposed between saidforward part and said rear part for holding said forward part in saidextended position, whereby said movable contact member becomes shorterwhen moved into contact with said other contact.

2. A high-voltage circuit breaker of claim 1 connected into ahigh-voltage line for switching the same, said breaker comprisingprimary switch actuation means connected to said common drive forclosing said primary switch at the end of a time period after saidauxiliary switch is closed, said time period being determined by saidresistor and the capacitance and characteristic impedance of the lineswitched by the breaker.

3. A high-voltage circuit breaker according to claim 1 comprising anadditional primary switch connected to said common drive and anadditional auxiliary switch connected to said common drive, each of saidadditional switches being driven by said common drive and being disposedsymmetrically with respect to corresponding ones of said first mentionedprimary and auxiliary switches.

4. A high-voltage circuit breaker comprising a primary switch; anauxiliary switch; and a resistor connected in series with said auxiliaryswitch, the serial combination of said resistor and said auxiliaryswitch being connected in parallel with said primary switch; mechanicaldrive means comprising a common drive movable to different positions foractuating said switches; said auxiliary switch comprising a spring forholding said auxiliary switch in the open position; and force-coupledconnection means for force-coupling said drive to said auxiliary switchand for disengaging said drive in dependence upon the position of saiddrive, said common drive being a rotatable drive shaft, saidforce-coupled said connection means comprising a rod connected to saidauxiliary switch and having a slot therein, a 'crank mounted on saiddrive shaft and having a crank pin engaging said slot, and blockingmeans for blocking the free movement of said pin in said slot independence upon the position of'said crank so as to provide a removableforce-coupled connection between said shaft and said auxiliary switch,whereby said crank actuates said auxiliary switch via said rod whenrotated by said drive shaft and when said pin is blocked.

5. The high-voltage circuit breaker of claim 4, wherein said crank isrotatable by said shaft between end positions, and wherein said rod hasan end connected to said auxiliary switch, said blocking meanscomprising a stop cam articulately joined at said end of said rod andblocking the free movement of said crank pin in said slot in dependenceupon the position of said crank, and a cam spring pressing against saidstop cam for holding said cam in a blocking position to block said crankpin, and displacement means for overcoming the force of said cam springand displacing said stop cam from said blocking position when said crankreaches one of said end positions thereby removing the block to the freemovement of said crank pin in said slot.

6. The high-voltage circuit breaker of claim 5, said cam spring being aleaf spring.

7. The high-voltage circuit breaker of claim 5, comprising a housingsurrounding said drive shaft and said force-coupled connection means,said housing having an inner wall surface, said displacement meanscomprising an abutment formed on said inner surface, and a projectionextending laterally from said stop cam, said projection having a lengthsufficient to strike said abutment and displace said stop cam againstthe force of said cam spring when said crank reaches said one endposition.

8. A high-voltage circuit breaker comprising a primary switch; anauxiliary switch; and a resistor connected inseries with said auxiliaryswitch, the serial combination of said resistor and said auxiliaryswitch being connected in parallel with said primary switch;and-mechanical drive means for actuating said switches, said mechanicaldrive means including a drive movable between first and second positionsfor opening and closing said primary switch, a spring for spring holdingsaid auxiliary switch in the open position thereof, force-coupledconnection means for transmitting a force from said drive to saidauxiliary switch sufficient to overcome the resisting force of saidspring and to close said auxiliary switch before said drive closes saidprimary switch and to then reopen said auxiliary switch after said drivecloses said primary switch in the movement of said drive to said secondposition, and means for disengaging said force-coupled connection meansfrom said drive in dependence upon the position of said drive in themovement from said first position to said second position whereby theforce of said spring acts on said auxiliary switch to spring hold thesame in said open position thereof and whereby said auxiliary switch isnot actuated when said drive returns from said second position to saidfirst position to open said primary switch.

9. The high-voltage circuit breaker of claim 8, said drive being arotatable drive shaft, said force-coupled connection means comprising arod connected to said auxiliary switch and having a slot therein, acrank mounted on said drive shaft and having a crank pin engaging saidslot, said means for disengaging said forcecoupled connection meansincluding blocking means for blocking the free movement of said pin insaid slot in dependence upon the position of said crank so as to.provide a removable force-coupled connection between said shaft andsaid auxiliary switch whereby said crank actuates said auxiliary switchvia said rod when rotated by said drive shaft and when said pin isblocked.

10. The high-voltage circuit breaker of claim 9 wherein said crank isrotatable by said shaft between end positions corresponding to saidfirst and second positions, and wherein said rod has an end connected tosaid auxiliary switch, said blocking means comprising a stop camarticulately joined at said end of said rod and blocking the freemovement of said crank pin in said slot in dependence upon the positionof said crank, and a cam spring pressing against said stop cam forholding said cam in a blocking position to block said crank pin, anddisplacement means for overcoming the force of said cam spring anddisplacing said stop cam from said blocking position when 'said crankreaches the end position corresponding to said second position therebyremoving the block to the free movement of said crank pin in said slot.

11. The high-voltage circuit breaker of claim 10, said cam spring beinga leaf spring.

12. The high-voltage circuit breaker of claim 10, comprising a housingsurrounding said drive shaft and said force-coupled connection means,said housing having an inner wall surface, said displacement meanscomprising an abutment formed on said inner wall surface, and aprojection extending laterally from said stop cam, said projectionhaving a length sufficient to strike said abutment and displace saidstop cam against the force of' said cam spring when said crank reachessaid end position corresponding to said second position.

13. The high-voltage circuit breaker of claim 8,said auxiliary switchcomprising a set of two contacts, at least one of said contacts being amovable contact connected to said force-coupled connection means forcontacting the other of said contacts in a butt-like manner when saidauxiliary switch is closed, said movable contact being a compositemember comprising a rear part connected to said force-coupled connectionmeans, a forward part for contacting said other contact, said forwardpart being longitudinally displaceable with respect to said rear part toan extended position for increasing the total length of said movablecontact, and a spring disposed between said forward part and said rearpart for holding said forward part in said extended position, wherebysaid movable contact member becomes shorter when moved into contact withsaid other contact.

14. A high-voltage circuit breaker of claim 8 connected into ahigh-voltage line for switching the same, said breaker comprisingprimary switch actuation means connected to said common drive forclosing said primary switch at the end of a time period after saidauxiliary switch is closed, said time period being determined by saidresistor and the capacitance and characteristic impedance of the lineswitched by the breaker.

15. A high-voltage circuit breaker according to claim 8 comprising anadditional primary switch connected to said common drive and anadditional auxiliary switch connected to said common drive, each of saidadditional switches being driven by said common drive and being disposedsymmetrically with respect to corresponding ones of said first mentionedprimary and auxiliary switches.

16. A high-voltage circuit breaker of claim 4 connected into ahigh-voltage line for switching the same, said breaker comprisingprimary switch actuation means connected to said common drive forclosing said primary switch at the end of a time period after saidauxiliary switch is closed, said time period being determined by saidresistor and the capacitance and characteristic impedance of the lineswitched by the breaker.

17. A high-voltage circuit breaker according to claim 4 comprising anadditional primary switch connected to said common drive and anadditional auxiliary switch connected to said common drive, each of saidadditional switches being driven by said common drive and being disposedsymmetrically with respect to corresponding ones of said first mentionedprimary and auxiliary switches.

UNITED STATES PATENT AND TRADEMARK OFFICE QERTIFICATE OF CORRECTIONPATENTNO.: 3,763,340 I Q DATED October 2, 1973 Page 1 of 2 INVENTOR(S) IDieter Noack It IS certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

I n the Drawing:

Sheet 2, Fig. 2, the illustration of element 23 was incorrect.Substitute the attached sheet 2, Fig. 2 for Q that in the patent.

' V j Signed and Scaled this twenty-fifth D3) 0f May 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (ommissinner oflaremsand Trademarks .l c r rin .m

1. A high-voltage circuit breaker comprising a primary switch; anauxiliary switch; and a resistor connected in series with said auxiliaryswitch, the serial combination of said resistor and said auxiliaryswitch being connected in parallel with said primary switch; mechanicaldrive means comprising a common drive movable to different positions foractuating said switches; said auxiliary switch comprising a spring forholding said auxiliary switch in the open position; and force-coupledconnection means for force-coupling said drive to said auxiliary switchand for disengaging said drive in dependence upon the position of saiddrive, said auxiliary switch further comprising a set of two contacts,at least one of said contacts being a movable contact connected to saidforce-coupled connection means for contacting the other of said contactin a butt-like manner when said auxiliary switch is closed, said movablecontact being a composite member comprising a rear part connected tosaid forcecoupled connection means, a forward part for contacting saidother contact, said forward part being longitudinally displaceable withrespect to said rear part to an extended position for increasing thetotal length of said movable contact, and a spring disposed between saidforwarD part and said rear part for holding said forward part in saidextended position, whereby said movable contact member becomes shorterwhen moved into contact with said other contact.
 2. A high-voltagecircuit breaker of claim 1 connected into a high-voltage line forswitching the same, said breaker comprising primary switch actuationmeans connected to said common drive for closing said primary switch atthe end of a time period after said auxiliary switch is closed, saidtime period being determined by said resistor and the capacitance andcharacteristic impedance of the line switched by the breaker.
 3. Ahigh-voltage circuit breaker according to claim 1 comprising anadditional primary switch connected to said common drive and anadditional auxiliary switch connected to said common drive, each of saidadditional switches being driven by said common drive and being disposedsymmetrically with respect to corresponding ones of said first mentionedprimary and auxiliary switches.
 4. A high-voltage circuit breakercomprising a primary switch; an auxiliary switch; and a resistorconnected in series with said auxiliary switch, the serial combinationof said resistor and said auxiliary switch being connected in parallelwith said primary switch; mechanical drive means comprising a commondrive movable to different positions for actuating said switches; saidauxiliary switch comprising a spring for holding said auxiliary switchin the open position; and force-coupled connection means forforce-coupling said drive to said auxiliary switch and for disengagingsaid drive in dependence upon the position of said drive, said commondrive being a rotatable drive shaft, said force-coupled said connectionmeans comprising a rod connected to said auxiliary switch and having aslot therein, a crank mounted on said drive shaft and having a crank pinengaging said slot, and blocking means for blocking the free movement ofsaid pin in said slot in dependence upon the position of said crank soas to provide a removable force-coupled connection between said shaftand said auxiliary switch, whereby said crank actuates said auxiliaryswitch via said rod when rotated by said drive shaft and when said pinis blocked.
 5. The high-voltage circuit breaker of claim 4, wherein saidcrank is rotatable by said shaft between end positions, and wherein saidrod has an end connected to said auxiliary switch, said blocking meanscomprising a stop cam articulately joined at said end of said rod andblocking the free movement of said crank pin in said slot in dependenceupon the position of said crank, and a cam spring pressing against saidstop cam for holding said cam in a blocking position to block said crankpin, and displacement means for overcoming the force of said cam springand displacing said stop cam from said blocking position when said crankreaches one of said end positions thereby removing the block to the freemovement of said crank pin in said slot.
 6. The high-voltage circuitbreaker of claim 5, said cam spring being a leaf spring.
 7. Thehigh-voltage circuit breaker of claim 5, comprising a housingsurrounding said drive shaft and said force-coupled connection means,said housing having an inner wall surface, said displacement meanscomprising an abutment formed on said inner surface, and a projectionextending laterally from said stop cam, said projection having a lengthsufficient to strike said abutment and displace said stop cam againstthe force of said cam spring when said crank reaches said one endposition.
 8. A high-voltage circuit breaker comprising a primary switch;an auxiliary switch; and a resistor connected in series with saidauxiliary switch, the serial combination of said resistor and saidauxiliary switch being connected in parallel with said primary switch;and-mechanical drive means for actuating said switches, said mechanicaldrive means including a drive movable between first and second positionsfor opening and closing said primary switch, a sPring for spring holdingsaid auxiliary switch in the open position thereof, force-coupledconnection means for transmitting a force from said drive to saidauxiliary switch sufficient to overcome the resisting force of saidspring and to close said auxiliary switch before said drive closes saidprimary switch and to then reopen said auxiliary switch after said drivecloses said primary switch in the movement of said drive to said secondposition, and means for disengaging said force-coupled connection meansfrom said drive in dependence upon the position of said drive in themovement from said first position to said second position whereby theforce of said spring acts on said auxiliary switch to spring hold thesame in said open position thereof and whereby said auxiliary switch isnot actuated when said drive returns from said second position to saidfirst position to open said primary switch.
 9. The high-voltage circuitbreaker of claim 8, said drive being a rotatable drive shaft, saidforce-coupled connection means comprising a rod connected to saidauxiliary switch and having a slot therein, a crank mounted on saiddrive shaft and having a crank pin engaging said slot, said means fordisengaging said force-coupled connection means including blocking meansfor blocking the free movement of said pin in said slot in dependenceupon the position of said crank so as to provide a removableforce-coupled connection between said shaft and said auxiliary switchwhereby said crank actuates said auxiliary switch via said rod whenrotated by said drive shaft and when said pin is blocked.
 10. Thehigh-voltage circuit breaker of claim 9 wherein said crank is rotatableby said shaft between end positions corresponding to said first andsecond positions, and wherein said rod has an end connected to saidauxiliary switch, said blocking means comprising a stop cam articulatelyjoined at said end of said rod and blocking the free movement of saidcrank pin in said slot in dependence upon the position of said crank,and a cam spring pressing against said stop cam for holding said cam ina blocking position to block said crank pin, and displacement means forovercoming the force of said cam spring and displacing said stop camfrom said blocking position when said crank reaches the end positioncorresponding to said second position thereby removing the block to thefree movement of said crank pin in said slot.
 11. The high-voltagecircuit breaker of claim 10, said cam spring being a leaf spring. 12.The high-voltage circuit breaker of claim 10, comprising a housingsurrounding said drive shaft and said force-coupled connection means,said housing having an inner wall surface, said displacement meanscomprising an abutment formed on said inner wall surface, and aprojection extending laterally from said stop cam, said projectionhaving a length sufficient to strike said abutment and displace saidstop cam against the force of said cam spring when said crank reachessaid end position corresponding to said second position.
 13. Thehigh-voltage circuit breaker of claim 8, said auxiliary switchcomprising a set of two contacts, at least one of said contacts being amovable contact connected to said force-coupled connection means forcontacting the other of said contacts in a butt-like manner when saidauxiliary switch is closed, said movable contact being a compositemember comprising a rear part connected to said force-coupled connectionmeans, a forward part for contacting said other contact, said forwardpart being longitudinally displaceable with respect to said rear part toan extended position for increasing the total length of said movablecontact, and a spring disposed between said forward part and said rearpart for holding said forward part in said extended position, wherebysaid movable contact member becomes shorter when moved into contact withsaid other contact.
 14. A high-voltage circuit breaker of claim 8connected into a high-voltage line for switching the same, said breakercomprising primary switch actuation means connected to said common drivefor closing said primary switch at the end of a time period after saidauxiliary switch is closed, said time period being determined by saidresistor and the capacitance and characteristic impedance of the lineswitched by the breaker.
 15. A high-voltage circuit breaker according toclaim 8 comprising an additional primary switch connected to said commondrive and an additional auxiliary switch connected to said common drive,each of said additional switches being driven by said common drive andbeing disposed symmetrically with respect to corresponding ones of saidfirst mentioned primary and auxiliary switches.
 16. A high-voltagecircuit breaker of claim 4 connected into a high-voltage line forswitching the same, said breaker comprising primary switch actuationmeans connected to said common drive for closing said primary switch atthe end of a time period after said auxiliary switch is closed, saidtime period being determined by said resistor and the capacitance andcharacteristic impedance of the line switched by the breaker.
 17. Ahigh-voltage circuit breaker according to claim 4 comprising anadditional primary switch connected to said common drive and anadditional auxiliary switch connected to said common drive, each of saidadditional switches being driven by said common drive and being disposedsymmetrically with respect to corresponding ones of said first mentionedprimary and auxiliary switches.